Method of detinning tin-scrap.



No. 859,566. PATBNTED JULY 9, 1907.

' M. LEITCH.

METHOD OF DETINNING TIN SCRAP. APPLICATION rmm un. a0, 1906.

3 SHEETS-SHEET 1.

No. 859,566. PATENTED JULY 9, 1907.

M. LBITGH.

METHOi) 0P DETINNING TIN SCRAP. APPLIOATION FILED APR-20, 1906.

' a sHBBTs-snnm 2.

PATENTED JULY 9, 1907.

M. LEITGH. METHOD OF DBTINNING TIN SCRAP.

APPLICATION FILED APR. 20, 1906.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFIGE.-

MEREDITH LEITOH, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO AMERICAN CAN COMPANY, OF JERSEYCITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF DETINNING TIN-SCRAP.

Specification of Letters Patent.

Patented July 9, 1907.

Originalapplioation filed February 17,1906, Serial No. 301,685. Divided and this application filed April 29, 1906.

. Serial No. 812.759.

T all whom it mag concern: Be it known that I, MEREDITH Lnrrcn, a citizen of the United Sates, residing at Elizabeth, Union county, New Jersey, have invented certain new and useful Improvements in Methods of Detinning Tin-Scrap, of

which the following is a full,- clear, and exact description.

My invention relates to improvements in methods of removing the tin coating from scrap tin, including tin cuttings, tin cans, and the like. I s

' In detinning plants as now constituted; scrap tin is usually deposited in baskets which are then immersed in electrolytic baths, there subjected to the action of an electric current, and subsequently removed by hand or by hoists of some suitable construction, after which the detinned or black scrap is immersed in wash tanks; the-apparatus requiring for the handling'of the scrap A. during this process hoists, baskets, tanks, cars, trucks and turn-tables, and manual labor at the various stages.

The object of my invention is to produce an efiicient method which shall be continuous in its operation and shall eliminate all manual labor in the detinning process, except that required to feed the scrap into a hop,- per and collect the tin powder from the cathode plates.

It further has for its object to reduce the cost of the electrolyte by thorough draining of the scrap,and by thorough washing, and to reduce the cost of regenerat ing the electrolyte by reducing its erfposure to the at mosphere, thus preventing the absorption of carbonic so acid.

It further has for its object to effect a more complete detinning by subjecting the scrap in one bath to the same conditions of current strength and heat and almost uniform position with relation toflow of the electric current and electrolyte.

It further has for its object to produce an easily collectible tin powder almost 'free from foreign matter by dpositing it only upon removable cathode plates, the refuse being allowed to precipitate to the bottom of the 40 tank.

The following is a description of the apparatus for carrying out my invention, reference being had to the accompanying drawings, in which Figure 1 shows the apparatus partly in vertical section and partly in side elevation. Fig. 2 represents a horizontal section of the same on the line x-x, Fig. 1. Fig. 3 represents an end elevation with 'partsbroken away. Fig. 4 represents a horizontal section of the apparatus on the line yg, Fig. 1. Figs. 5 and 6 represent diagrammatically in plan and side eleyation the system embodying-the electrolytic and washing baths.

Referring more particularly to the drawings, A represents a tank, preferably of iron, designed to rest on the floor or the floor of a pit, and electricallyinsulated at a a so as to remain neutral with reference to the electric 5 5 circuit hereinafter described, even when that circuit is fore been used in electrolytic detinning. 1 The .tankA is provided with an inlet'D and an outlet E, and supply I and return pipes D and E disconnected or otherwise insulated therefrom for the circulation of the heated electrolyte. There is also a draw-off pipe F at the bottom of the tank for completely emptying the same, and

a clean-out door G for removing the precipitated waste: Within this tank there is a stationary receiver H, which,

in its preferred form, is a U-shaped basket or tube, as shown, preferably of iron, which is to receive and support the tin scrap.

The U-shaped basket is provided at the left-hand side with a hopper I into which the tin scrap is fed. The sides of the basket or tube are made of sheet metal, perforated as at h. The curved bottom is made of sheetmetal, but is imperforate so as to prevent the sifting out of particles that may be present. The ends H are preferably of perforated cast metal having flanges h to which the perforated sides of the basket H are secured in such a way as to avoid any roughness on the inside of the tube or basket. These ends are provided with raised portions J in which are formed grooves to receive conveyer chains K. The grooves at the lower part of the tube are curved as shown at J. and the inner curved surfacesof the grooves are formed by smooth-rimmed wheels L mounted on the outside of the tube or basket H, but having their rims projecting through slots in the castings in such a way that the rims of the-wheels form the inner curved surfacesof the grooves, thus providing means for turning and guiding the chains around the curve without any friction and without catching the tin scrap. The wheels L are mounted in suitable bearings M M carried by the basket H. Fastened to the chains are. T-bars N N, which, when the chains are in motion, serve to convey the scrap down and up through the U-shaped basket and through an imperforate upward extension}? of the tube and over the top to the dis-' charge chute H from'which the scrap will glide by gravity into the black scrap conveyor 0. i The Qconveyer O is designed to receive the detinned or black scrap from a number of baths as they discharge, and deliver'it to a washer or series of washerssi'milar in construction to the detinning bath, or to such point as may be desired. In passingto the discharge chute the conveyor chains pass over sprocket wheels P,

which project through slots in the castings in the'same Q manner as do the wheels L and thus form the inner curved surfaces of the grooves at the points where they are located. The sprocket teeth engage the chains and impart motion thereto, power being supplied from any suitable source. The conveyer chains, after leaving the discharge chute, pass over idlers Q and R, supported on wooden beams or otherwise insulated, and then return to the U-shaped basket H. Immersed in the electrolyte within the tank are three cathodes, S, S and S preferably of iron, which are provided with extensions S S and S which rest upon conductors V V connected to the negative pole of a source of electricity. The cathodes S, S and S can thus be removed and replaced by simply lifting them out of the tank without disturbing the other parts, the upper extensions H being at least long enough so that there .will be nothing to interfere with the removal of the cathode S The hopper I is hinged at i so that it can be turned up out of the way of the cathode S. Normally it rests against the upright i of wood or other poor conducting material. The basket H is per= mancntly electrically connected by the supporting lugs H to the conductors W W, and the positive pole of the source of electricity so that its contents form the anode in the electrolytic cell.

In Figs. 5 and 6, A A are detinning baths discharging tinned or black scrap into the conveyer O. The discharge into the conveyer is slow and, if not steady, is

at frequent intervals. The conveyer carries the detinned scrap to the washers 1, 2, 3, each of which has a basket similar tothat in the bath A (Fig. 1). The neighboring washing baskets are connected and through all of them runs a common conveyer K (shown onlyin Fig. 6). Power is applied to the conveyer as it comes from each washing basket through the wheels P P P. The tanks of the baths 1, 2, 3, are supplied with running water, fed to the last tank at 4, and flowing through the washing tanks in theopposite direction to the movement of the black scrap until it flows through connections 5 and 6 and out of the first tank at 7. Each washing tank is provided with a diaphragm 8 extending clear across and as near to the bottom as the basket or tubes will permit, so as to direct the flow of the water. The tin scrap is in this way detinned and washed without manual labor other than that necessary is therefore protected against any but accidental groundingthrough the chute or conveyer as well as at other points. This is of particular importance where the electrolytic apparatus are electrically in Seriesand mechanically in multiple as shown in Fig. 5, which is the preferred arrangement. I

In operating the apparatus, a caustic soda solution heated to about 75 centigrade is caused to circulate through the tank A. The tin scrap is then fed into the hopper I sufficiently fast sothat the basket when once filled is kept full. The conveyer chain K is then operated through the sprocket wheels P-with either a'steady or a periodic movement, so that a substanfree from tin powder, except as the same may be disthe conveyer chains with the T-bars move, the scrap as it leaves the bath is permitted to drain to a greater or less degree according to the length of the upper extension H and the rate of movement of the chains. In this way the greater part of the electrolyte flows immediately back to the tank A. The form of the apparatus results ina comparatively slight exposure of the electrolyte to the air, and at the same time permits it to be easily surrounded by a non-conductor of heat. When the tank is so.'surrounded, as well as the pipes conducting the electrolyte to and from the same, as indicated at H, the loss of heat by radiation is reduced to a minimum. The permanent electric connections and electro-chemical relations of the elements in the bath are such as to make the resistance comparatively low, and thus save electrical energy. Scrap is removed as fast as it is detinned, and fresh scrap is simultaneously introduced, so that the resistance of the bath and the working conditions are always substantially the same. The scrap which passes through the bath is all subjected to the same conditions of current and heat, being almost uniform in position with relation to the flow of electrical current and electrolyte. Moreover, the scrap in going through the basket is turned upside down, permitting the escape of any confined air, and also a more complete circulation of the electrolyte. The scrap, when the tin has been removed, is carried to the washers. Moreover, the scrap is inverted or reversed in position while passing through each washing tank and is also inverted or reversed in position while passing through the air in going from one washing tank to another. The emptying of the cans between each bath insures a more complete Washing of their interiors.

ode plates only, the tank itself being neutral. The

refuse falls'to the bottom of the tank and is therefore lodged from the cathodes.

My invention permits of being carried out by appa ratus modified, both in form and in materials used,

such as would suggest themselves to those skilled in the art. The apparatus which I have shown and described is, however, the form preferred by me; ,'This is a division of my application, Serial No. 301,585, filed February 17, 1906.

What I claim is:-

1. In the process of detinning tin, scrap consisting of old tin cans and the like, the improvement which consists in passing the scrap downward through the liquid of a bath with a substantially continuous movement for a considerable distance, releasing confined air by inverting that part of the mass that is lowermost, said part being but a small portion of the submerged mass, and then bringing the scrap to the surface by substantially continuous movement.

2. In the process of detinning tin scrap consisting of old tin cans and the like, the improvement which consists in passing the scrap downward through the liquid of; a bath with a substantially continuous movement for a considerable distance, releasing confined air by inverting that part of the mass that is lowermost, said part being but a small portion of the submerged mass, and then bringing the scrap to the surface by a substantially continuous movemeant, meanwhile subjecting said scrap while within said bath to electrolytic action 3. 'llhe improvement in the process of detinning tin scrap consisting of old tin cans and the like which consists in passing it through a detinning bath with a substantially continuous movement, and then passing saidscrap substantially continuously through a washing bath and releasing confined air from said scrap while in said washing bath by inverting it.

4. The improvement in the process of detinning tin scrap consisting of old tin cans and the like which consists in passing said scrap with a substantially continuous movement through a detinning bath and passing said scrap substantially continuously through a series of washing baths,- emptying out contained liquid from said scrap by inverting it while passing from one washing bath to another.

tin cans and the lilge, the improvement which consists in passing it through a detinning bath and then through a series of washing baths, inverting said scrap while in said washing bath so as to release confined air and inverting it while passing from one washing bath to another so as to. empty out any contained liquid.

MEREDITH LEITCH. Witnesses HARRY L. Sonny, ARTHUR H. Arena. 

